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 ###Instrução: Qual é o metal de cunhagem para números de KM de S45?
 ###Tabelas: CREATE TABLE 20th-_and_21st-century_swiss_confederation_issues (20th-_and_21st-century_swiss_confederation_issues_id AUTO_INCREMENT PRIMARY KEY, Location VARCHAR, Date INT, Denomination VARCHAR, Coinage metal VARCHAR, Mintage INT, KM number VARCHAR) CREATE TABLE members_of_the_parliament (members_of_the_parliament_id AUTO_INCREMENT PRIMARY KEY, Lok Sabha VARCHAR, Duration VARCHAR, Name of M.P. VARCHAR, Party Affiliation VARCHAR, Election Year INT) CREATE TABLE nonstructural_viral_proteins (nonstructural_viral_proteins_id AUTO_INCREMENT PRIMARY KEY, RNA Segment (Gene) INT, Size ( s base pair ) INT, Protein VARCHAR, Molecular weight kDa VARCHAR, Location VARCHAR, Copies per particle VARCHAR) CREATE TABLE senators_at_the_beginning_of_the_39th_parliament (senators_at_the_beginning_of_the_39th_parliament_id AUTO_INCREMENT PRIMARY KEY, Name VARCHAR, Party VARCHAR, Province (Division) VARCHAR, Date appointed VARCHAR, Appointed by VARCHAR, Left office VARCHAR) CREATE TABLE winning_head_of_the_river_championship_events (winning_head_of_the_river_championship_events_id AUTO_INCREMENT PRIMARY KEY, Crew INT, Open 1st VIII VARCHAR, Open 2nd VIII VARCHAR, Open 3rd VIII VARCHAR, U16 1st VIII VARCHAR, U16 2nd VIII VARCHAR, U16 3rd VIII VARCHAR, U15 1st IV VARCHAR, U15 2nd IV VARCHAR, U15 3rd IV VARCHAR, U15 4th IV VARCHAR, U15 5th IV VARCHAR, U15 6th IV VARCHAR)  
SELECT Coinage metal FROM 20th-_and_21st-century_swiss_confederation_issues WHERE KM number = S45